Washington, Apr 27 (IANS): The parents of American student Otto Warmbier filed a wrongful death lawsuit against the North Korean government charging that the country's regime tortured and killed their son, according to lawyers for the family.

Warmbier -- the 22-year-old American student who was detained in North Korea for 17 months -- was returned to his family "with severe brain damage and in a non-responsive state" in June 2017, reports CNN.

He died on June 19, 2017.

"Otto was taken hostage, kept as a prisoner for political purposes, used as a pawn and singled out for exceptionally harsh and brutal treatment by Kim Jong Un," his father Fred Warmbier, said in a statement on Thursday.

"Kim (Jong-un) and his regime have portrayed themselves as innocent, while they intentionally destroyed our son's life. This lawsuit is another step in holding North Korea accountable for its barbaric treatment of Otto and our family," the statement said.

The suit comes at a sensitive moment for US-North Korean relations, with President Donald Trump due to meet face-to-face with the North Korean leader sometime next month.

In the lawsuit, Warmbier's attorneys outlined how escalating tensions between the Obama and Trump administrations and North Korea coincided with the student's detention.

Congress passed banking sanctions in response to Warmbier's death late last year, and Trump re-designated the country as a sponsor of terrorism in November, which allowed the Warmbiers to sue the foreign government.

Otto was taken into custody by North Korean authorities during a five day sightseeing tour of the reclusive state, who accused him of stealing a political poster from a restricted floor on his hotel, CNN reported.

He was sentenced to 15 years of hard labour.

When Otto arrived back in the US he was in a persistent vegetative state but North Korea claimed he had contracted botulism while in prison.

The Hamilton County Coroner's office in Ohio released a report in September 2017 outlining the findings of an external examination of the student's body.

The lawsuit filed on Thursday describes in detail their encounter with their son when he landed in Cincinnati after his medical evacuation from North Korea.

The parents noticed he was blind, deaf, had a shaved head and a feeding tube, "was jerking violently and howling" and had misaligned teeth, the lawsuit added.